Meat saw



A. N. BLUM April 14,v 1942.

MEAT SAW Filed No'v, 4, 1939 Patented Apr. 14, i942 UNITED STATES PATENT OFFICE MEAT SAW Arthur N. Blum, Philadelphia, Pa. Application November 4, 1939, Serial No. v302,918

l Claims.

This invention relates to improvements in meat saws and saws of like type.

The principal object of the invention is to providein a saw of this class improved means of adjustment for attaining a proper tensioning of the saw blade inthe frame.

Another object of the invention is to provide a frame for saws of this type including means for automatically compensating excessive strains imposed upon the frame by the tensioning of the blade to prevent said strains from transversely distorting the frame.

The invention further resides in certain novel structural features hereinafter described and illustrated in the attached drawing, in which:

Figure 1 is aside View of a saw made in aceordance with my invention;

Fig. 2 is an enlarged fragmentary and partial sectional View of the handle end of the saw;

Fig. 3 is an enlarged fragmentary view of a terminal end of the frame and of the adjustable blade-clamping elements;

Fig. 4 is a plan view of the fragment shown in Fig. 3;

Fig. 5 is a section on the line 5 5, Fig. 3;

Figs, 6 and '7 are detached views in perspective of elements of the blade-clamping device;

Fig. 8 is a detached side View of the bladeretaining lever illustrating a modification within the scope of the invention;

Fig. 9 is a section on the line 9-9, Fig. 8, and

Fig. l is a fragmentary perspective view of the outer terminal end of the frame shown in Fig. 1.

With reference to the drawing, the saw illustrated comprises the usual frame or back I, to one end of which is secured a handle 2. As illustrated in Fig. 2, that portion of the frame I which is embraced by the handle 2 is provided in its outer edge with a recess 3, the inner edge of this recess preferably extending on a line parallel to the opposite or inner edge of the frame. The function of this recess will be hereinafter described.

The outerterminal end that end of the frame of the frame I, i. e., remote to the handle 2, is provided with a. pin 4 adapted to engage in a perforation at one end of the saw blade to anchor that end of the blade to the frame, and as shown in Fig. 10, the frame is provided at the end with a slot which when the blade is in the normal assembled position prevents transverse displacement of the blade from the pin 4. The opposite end of the frame I`, which is also slotted for reception of the bl-ade 5, as indicated in Fig. 3, is provided with a pivoted lever 6, this lever being shown in perspective in Fig. 6. As therein illustrated, the lever E has bifurcations 'I and 8 which in assembly occupy positions at opposite sides of the -extremity of the frame I, and these bifurcations are in the present instance provided with aligned threaded apertures 9, 9 which receive screws Iii, It by means of which the lever is pivotally secured to the frame I. As shown in Fig. 4, the screws I0, IU are formed with inner ends adapted to project into the opposite ends of an aperture in the frame I, or into cylindrical recesses formed in opposite sides of the frame, to thereby form trunnions pivotally supporting the lever on the frame. The body of the lever 6 from which the bifurcations 'I and 8 extend is provided with an opening II for reception of a suitable tool, such for example as a steel rod or a butchers steel, forming la handle with increased leverage for operating the lever about its pivot, as hereinafter more fully described.

As best shown in Fig. 6, the bifurcation 8 is extended at I2 toward the body end of the lever, and this flange I2 is provided with an opening I3 which in the present instance is hexagonal in form. This opening I3 is adapted to receive a correspondingly shaped extension I4 projecting axially from one face of a disk I5, and this disk is provided on its opposite face 4with a pin I6 positioned eccentrically with respect to the axis of the disk and adapted to engage in an aperture at the inner or handle end of the saw blade 5.

vExtending axially from the face of the hexagonal projection I4 is a stem I'I having intermediate its ends a threaded section i8 and having riveted to its extremity a washer I9. Embracing the stem I'I and having threaded engagement with Vthe threaded section I8 of the stem `is a nut 2D, thus nut having at its outer 'end a re' cess 2| which receives the washer I9. When, 'as shown in Fig. 5, the nut 2li is turned in Vagainst the flange I2 o the lever 6, the disk I'Sis -held securely against ythe opposite face of the flange, and the hexagonal portion I4 fittingrin the cor'- respondingly shaped opening in the 'flange -prevents rotation ofthe disk about its axis. When the nut 20 is' backed off upon the threaded section I8 of the stem I'I, the disk I5 and stemrl'I may be moved axially to an extent freeing fthe hexagonal section I4 from the opening `|13 `to thereby permit rotational adjustment of thedis'k with respect to .the an'ge I2. 'It will be not'ed that the arrangement-provides for the required adjustment of the nut 20 on the stem while at the same time preventing removal of the nut from the vstem or removal of the stem from the flange I2.

With reference to Figs. l, 2 and 3, it Will be noted that in normal assembly and with the lever 6 turned back so that the portion 6a thereof between the bifurcations 'I and 8 is in abutment with the outer edge of the frame I, the pins 4 and I6 are slightly out of alignment with the pivotal axis of the lever screws I0, the arrangement being such that the tension of the saw blade 5 tends to lock the lever 6 by toggle action in this position, which toggle action is limited and controlled by the abutment 6a. Release of the blade 5 may be eiected by adjusting the lever 6 toward the position in which it is shown in broken lines in Fig. 3. Since normally the tension upon the blade 5 is considerable, this adjustment of the lever breaking the toggle formed by the pins 4 and I6 and the pivot I requires considerable force, and the operation is facilitated by provision in the lever 6 of the opening II, which as previously described is adapted to receive an implement affording an advantageous leverage for adjusting the lever toward both the 'blade-releasing and blade-locking positions.

The toggle action is very desirable in saws of this class, since all adjustment is accomplished with one single motion of the hand. However, saw blades of this type frequently lack uniformity of length, or uniformity of spacing between the apertures at the extremities of the blade through the medium of which the blade is secured in the frame as described above. Under these conditions, the toggle action fails, as it evidently either gives too much tension or not enough. For this reason, it was heretofore oommon to attach the blade to a holder tted slidingly in the frame and provided with a screw at the other end. This screw in cooperation with a' nut or wing nut served to tensionthe blade and allowed for compensation of `variation in its length. However, such tensioning is slow and difficult owing to the fact that it must be done under tension and consequently with considerable exertion of force. Furthermore, the butcher, desiring as much tension as possible, would sometimes overtension and bend the frame permanently by tightening on the nut more than necessary. In my present invention, the compensation for variation in the blade length is not done under tension and, therefore, requires little exertion, and subsequently the blade is tensioned by a single motion of the toggle, thus combining the advantages of the lever'action with the adjustability of the screw and nut, and so eliminating the drawbacks of either system.

In my device, hereinbefore described, the position of the pin I6 with respect to the pin 4 at the opposite end ofthe frame may be adjusted within the limits imposed by the eccentricity of the pinvI6 with respect to the axis of rotation of the disk I and stem I1. This adjustment of the pin I6 is effected as set forth bybacking off the nut and releasing the hexagonal portion I4 from the opening I3. When the hexagonal portion rI4 is engaged in the aperture I3, it is apparent that the pin I6 is positively retained in its adjusted position. s Y

Should it occur that with the pin I6 in a given position of adjustment, the. tension of the saw blade. 5 will be excessive to lthepoint of actually causing a transverse distortion of 6 represented by the the frame I.l

Viously referred to frame in which Ilexure may occur under exces- In order to avoid this undesirable bending of the frame and to insure true alignment of the frame and the blade, I have utilized the recess 3 preto provide a section of the sive tension of the blade 5 in the normal plane of the frame. By disposing the recessed section in that portion of the frame embraced by the vhandle 2, there is no departure in appearance from the normal frame construction. This device has provedv adequate under all normal conditions to prevent the undesirable transverse distortion of the frame referred to.

In Figs. 8 and 9, I have illustrated a modiication within the scope of the invention. In this instance, the disk I 5a which carries the pin I 6a is slightly tapered at the periphery and nts in a correspondingly tapered recess in the iiange I2a of the lever 6a. From the inner end of the disk I5a, a threaded stem I1a extends through an aperture of the flange I2a and receives a nut 20a which when turned in against the adjoining face of the flange IZa draws the tapered disk I5a into its recess and by wedge action secures the disk in its axially adjusted position in the ange. As in the previouslydescribed embodiment, the device aiords adjustment of the pin I6a to properly tension the saw blade.

My invention, as illustrated in the aforedescribed embodiments, aiords substantial advantages over the prior art. It provides for convenient and quick change and positive and accurate tensioning of blades; and the fact that both ends of the blade occupy slots in the frame insures against accidental separation of the blade from the frame during the changing operations and in use. 'Ihe novel means for compensating for variations in blade length, which is adjustable while the blade is not under tension, is also both convenient and safe and provides for accurate tensioning of the blade with little danger of overloading the frame. It also provides a, safeguard in the recess 3 against damage to the frame or misalignments due to any slight overloading that may accidentally occur. The saw is free from loose and projecting parts, is simple in form and, therefore, readily cleaned and maintained in sanitary condition. Another feature of importance resides in the compactness of the tensioning device which allows the saw handle to be located as near as possible to the center of gravity of the saw, and thereby reduces to a minimum the energy required for operating the saw in its normal function.

There may be other modifications without departure from the invention.

I claim:

1. A saw comprising a substantially U-shaped frame, and means for securing a saw blade under tension between the extremities of said frame, said means comprising a tensioning member movably mounted at one extremity of the frame, a stud extending transversely through a polygonal opening in said member, said stud having a head portion adapted to engage one face of said member, an axially arranged polygonal portion adjoining said head and fitting the said opening, a nut threaded on the opposite end of said stud and adapted to bear against the opposite face of said member tosecure the stud in position, and a blade-retaining pin projecting from said head in a Aposition eccentric to the axis of the stud, the polygonal portion of said stud being releasable from said opening by loosening of the nut to permit adjustment of` the stud about its axis to thereby vary the effective distance of said pin from the remote extremity of the frame.

2. A saw comprising a substantially U-shaped frame, and means for securing a saw blade under tension between the extremities of said frame, said means comprising a tensioning member movably mounted at one extremity of the frame, and a stud extending transversely through an opening in said member, said stud comprising a tapered head adapted to fit a correspondingly tapered countersunk recess in said member, a nut for drawing said head into the recess, and a blade-retaining pin projecting from said head in a position eccentric to the axis of said stud, said stud being adjustable about the axis to vary the effective distance of the pin from the remote extremity of the frame and being locked in .adjusted position by wedging action of the head in said recess through the medium of said nut.

3. A saw comprising a substantially U-shaped frame, and means for securing a saw blade under tension between the extremities of said frame, said means comprising a tensioning member movably mounted at one extremity of the frame, an element rotatably adjustable in said member on an axis transverse to the plane of the saw, coupling means for retaining said element in adjusted position and releasable to permit of said adjustment by axial movement of the element in said member, releasable means for normally restraining the element against said axial movement, anda blade-retaining pin eccentrically positioned on said element, the rotational adjustability of said element affording variation in the eiective distance of the pin from the remote extremity of the frame.

4. A saw -comprising a substantially U-shaped frame, and means for securing a saw blade under tension between the extremities of said frame, said means comprising a fulcrumed lever mounted at one extremity of the frame, an element rotatably adjustable in said lever, coupling means normally preventing rotation of said element and releasable by axial movement ofthe element in the lever, releasable means for locking said element against said axial movement, and a blade-retaining'pin eccentrically carried by said element,

l A saw comprising a substantially U-shaped frame, and means :for securing a saw blade under tension between the extremities of said frame, said means 4comprising a tensioning member movement of the element in movably mounted at one extremity of the frame and having a polygonal opening, an element rotatably adjustable in said Amember and having a polygonal portion to fit into the polygonal opening of the latter, said polygonal portion and opening constituting a coupling normally preventing the rotation of said element and being releasable to permit of said adjustment by axial the member, releasable means normally preventing said axial movement, and a blade-retaining pin eccentrically positioned on saidelement.

6. A saw frame having a blade-retaining slot at each end thereof, a stationary blade-retaining pin coperative with the slot at oneend of the frame to retain the blade against both longitudinal and transverse frame, a lever fulcrumed at the other end of the frame, an element rotatably adjustable in said lever, -coupling means normally preventing rotation of said element and releasable by axial movement of the element in the lever, releasable means for locking said element against said axial movement, an eccentrically disposed blade-retaining pin carried by said element, said lever being swingable to place the blade under tension in the frame, and said element being positioned in said lever with respect to the fulcrum so that when the lever is in blade-tensioning position the said fulcrum lies at one side of a straight line connecting said blade-retaining pins, thereby creating a toggle tending to retainthe lever in the said blade-tensioning position, said second-named pin and the adjoining frame slot cooperatively retaining the blade at that end of the frame against both longitudinal and transverse displacement from the latter,

7. A saw frame having blade-retaining means at one end, a blade-retaining and tensioning member movably attached to the opposite end of the frame, and means operatively connected with said member for compensating for variations in blade length, said compensating means comprising a stud seated in an opening in said tensioning member and carrying blade-retaining means eccentrically arranged on said stud,

and coupling means normally elective to prevent rotation of said stud in the member and releasable to permit rotatable adjustment of said stud by axial displacement of the stud in the member. t

ARTHUR N. BLUM.

displacement from the 

